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A general revision of the Palaemonidae (Crustacea decapoda natantia) of the Americas. 2. The subfamily Palaemoninae

A general revision of the Palaemonidae (Crustacea decapoda natantia) of the Americas. 2. The subfamily Palaemoninae, Subgenus Palaemon, p. 172

172 ALLAN HANCOCK FOUNDATION OCCASIONAL PAPERS
Material examined: In the Rijksmuseum van Natuurlijke Historie
at Leiden, Holland, material of this species is present from: Shrimp
traps in the mouth of the Surinam River near Resolutie, Surinam (December 22, 1942, D. C. Geijskes coll.), mouth of Warappa Creek near
Matappica, north bank of Commewijne River, just E. of Paramaribo,
Surinam (December 11, 1942, D. C. Geijskes coll.), shore of the Surinam River near Paramaribo, Surinam (December, 1949, D. C. Geijskes
coll.). Specimens from the first mentioned lot have been presented by
the Leiden Museum to the U. S. National Museum, Washington, D. C.
Type: Holotype is a specimen from the first mentioned lot ( Surinam
River near Resolutie). It is preserved in the Leiden Museum, where
also the larger part of the paratypes is stored. The rest of the paratypes
is in the possession of the U. S. National Museum.
Remarks: The present species is most closely related to Palaemon
(Nematopalaemon) tenuipes (Henderson) from India and Palaemon
(Nematopalaemon) hastatus Aurivillius from West Africa. The three
species are characterized by the enormous prolongation of the dactyli
of the last three legs, and differ in that respect from all other species of
Palaemon. Palaemon (Nematopalaemon) schmitti differs from P. tenuipes by having the rostrum longer, with less dorsal and more ventral
teeth. The rostral formula of P. schmitti is 3-4 + 1 of P. tenuipes it
7-9
is 4-6 4- 1 (Kemp gives 5 to 7 teeth for the basal crest, as he includes
2-6
the little notch behind the first tooth as a regular tooth). Furthermore,
the last joint of the third maxilliped in P. tenuipes is relatively shorter
than that in P. schmitti. Also the sixth abdominal segment in P. schmitti
is longer than that in P. tenuipes, being more than 2/3 of the length
of the carapace. Palaemon schmitti differs from the West African P.
hastatus in the rostral formula too. This formula in P. hastatus namely
is 7-11 +1. The carpus of the second legs in P. hastatus furthermore is
3-6
relatively longer than in the American species.
Subgenus PALAEMON Weber, 1795
The characters in which this subgenus differs from the other subgenera of the genus Palaemon are:
1. The rostrum never is provided with an elevated basal crest of
dorsal teeth.
2. The branchiostegal groove always is distinct.

172 ALLAN HANCOCK FOUNDATION OCCASIONAL PAPERS
Material examined: In the Rijksmuseum van Natuurlijke Historie
at Leiden, Holland, material of this species is present from: Shrimp
traps in the mouth of the Surinam River near Resolutie, Surinam (December 22, 1942, D. C. Geijskes coll.), mouth of Warappa Creek near
Matappica, north bank of Commewijne River, just E. of Paramaribo,
Surinam (December 11, 1942, D. C. Geijskes coll.), shore of the Surinam River near Paramaribo, Surinam (December, 1949, D. C. Geijskes
coll.). Specimens from the first mentioned lot have been presented by
the Leiden Museum to the U. S. National Museum, Washington, D. C.
Type: Holotype is a specimen from the first mentioned lot ( Surinam
River near Resolutie). It is preserved in the Leiden Museum, where
also the larger part of the paratypes is stored. The rest of the paratypes
is in the possession of the U. S. National Museum.
Remarks: The present species is most closely related to Palaemon
(Nematopalaemon) tenuipes (Henderson) from India and Palaemon
(Nematopalaemon) hastatus Aurivillius from West Africa. The three
species are characterized by the enormous prolongation of the dactyli
of the last three legs, and differ in that respect from all other species of
Palaemon. Palaemon (Nematopalaemon) schmitti differs from P. tenuipes by having the rostrum longer, with less dorsal and more ventral
teeth. The rostral formula of P. schmitti is 3-4 + 1 of P. tenuipes it
7-9
is 4-6 4- 1 (Kemp gives 5 to 7 teeth for the basal crest, as he includes
2-6
the little notch behind the first tooth as a regular tooth). Furthermore,
the last joint of the third maxilliped in P. tenuipes is relatively shorter
than that in P. schmitti. Also the sixth abdominal segment in P. schmitti
is longer than that in P. tenuipes, being more than 2/3 of the length
of the carapace. Palaemon schmitti differs from the West African P.
hastatus in the rostral formula too. This formula in P. hastatus namely
is 7-11 +1. The carpus of the second legs in P. hastatus furthermore is
3-6
relatively longer than in the American species.
Subgenus PALAEMON Weber, 1795
The characters in which this subgenus differs from the other subgenera of the genus Palaemon are:
1. The rostrum never is provided with an elevated basal crest of
dorsal teeth.
2. The branchiostegal groove always is distinct.